Variable speed hydraulic pump
First Claim
1. A variable speed hydraulic pump, comprising:
- a variable speed electric motor;
a hydraulic pump unit coupled to the electric motor and a hydraulic fluid source for pumping hydraulic fluid when operated by the motor; and
a motor controller electrically connected to the motor for supplying an electrical drive signal to the motor in response to an electrical motor load signal characteristic of said drive signal which varies dependent on the torque exerted by said motor, said electrical motor load signal characteristic being detected by said motor controller, and wherein said motor controller supplies said electrical drive signal so as to output a constant power to said pump over substantially the entire operating pressure range of said pump.
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Accused Products
Abstract
The invention provides a variable speed hydraulic pump designed to operate at a maximum horsepower throughout its pressure range by adjusting motor speed according to motor load parameters. In particular, the variable speed hydraulic pump includes a hydraulic pump unit coupled to a variable speed electric motor by a drive unit and to a hydraulic fluid tank for pressurizing and pumping hydraulic fluid when operated by the motor. A motor controller is electrically connected to the motor to supply drive signals to the motor based on electrical characteristics of the drive signals which are dependent on the load exerted on the motor. Suction from the load is provided by both the main pump and a bidirectional supercharging pump by reversing the direction of the motor and shifting a 4/3 valve to connect the main pump inlet to the load and its outlet to tank. In addition, the controller reduces the motor speed at the maximum rated pressure to just maintain the pressure, to reduce the amount of fluid pumped through the maximum pressure relief valve.
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Citations
20 Claims
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1. A variable speed hydraulic pump, comprising:
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a variable speed electric motor;
a hydraulic pump unit coupled to the electric motor and a hydraulic fluid source for pumping hydraulic fluid when operated by the motor; and
a motor controller electrically connected to the motor for supplying an electrical drive signal to the motor in response to an electrical motor load signal characteristic of said drive signal which varies dependent on the torque exerted by said motor, said electrical motor load signal characteristic being detected by said motor controller, and wherein said motor controller supplies said electrical drive signal so as to output a constant power to said pump over substantially the entire operating pressure range of said pump. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification